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perf_counter: x86: Fix throttling

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If counters are disabled globally when a perfcounter IRQ/NMI hits,
and if we throttle in that case, we'll promote the '0' value to
the next lapic IRQ and disable all perfcounters at that point,
permanently ...

Fix it.

[ Impact: fix hung perfcounters under load ]

Acked-by: Peter Zijlstra <a.p.zijlstra@chello.nl>
Cc: Paul Mackerras <paulus@samba.org>
Cc: Corey Ashford <cjashfor@linux.vnet.ibm.com>
LKML-Reference: <new-submission>
Signed-off-by: Ingo Molnar <mingo@elte.hu>
This commit is contained in:
Ingo Molnar
2009-05-13 12:54:01 +02:00
parent ec3232bdf8
commit f5a5a2f6e6
1 changed files with 15 additions and 5 deletions
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20
arch/x86/kernel/cpu/perf_counter.c
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@ -765,8 +765,13 @@ out:
/* /*
* Restore - do not reenable when global enable is off or throttled: * Restore - do not reenable when global enable is off or throttled:
*/ */
if (++cpuc->interrupts < PERFMON_MAX_INTERRUPTS) if (cpuc->throttle_ctrl) {
if (++cpuc->interrupts < PERFMON_MAX_INTERRUPTS) {
intel_pmu_restore_all(cpuc->throttle_ctrl); intel_pmu_restore_all(cpuc->throttle_ctrl);
} else {
pr_info("CPU#%d: perfcounters: max interrupt rate exceeded! Throttle on.\n", smp_processor_id());
}
}
return ret; return ret;
} }
@ -817,11 +822,16 @@ void perf_counter_unthrottle(void)
cpuc = &__get_cpu_var(cpu_hw_counters); cpuc = &__get_cpu_var(cpu_hw_counters);
if (cpuc->interrupts >= PERFMON_MAX_INTERRUPTS) { if (cpuc->interrupts >= PERFMON_MAX_INTERRUPTS) {
if (printk_ratelimit()) pr_info("CPU#%d: perfcounters: throttle off.\n", smp_processor_id());
printk(KERN_WARNING "perfcounters: max interrupts exceeded!\n");
hw_perf_restore(cpuc->throttle_ctrl); /*
} * Clear them before re-enabling irqs/NMIs again:
*/
cpuc->interrupts = 0; cpuc->interrupts = 0;
hw_perf_restore(cpuc->throttle_ctrl);
} else {
cpuc->interrupts = 0;
}
} }
void smp_perf_counter_interrupt(struct pt_regs *regs) void smp_perf_counter_interrupt(struct pt_regs *regs)